serial port communication via the userport

[mithrendal]

We've had serial port communication in vc64web, the web version of virtualC64, for a while now.

To make it easier to update to newer core versions and merge the code, I thought it would be a good idea to bring the serial port communication feature from vc64web over to virtualC64.

So, I've put in PR #800 for this.

[dirkwhoffmann]

I'm currently reimplementing the merged code to make it fit into the existing component architecture. I am also adapting the Commander interface from vAmiga which allows the emulated computer (the C64 in this case) to control RetroShell. An early prototype is already working.

Step 1: Activate the commander:

Step 2: Type a RetroShell command in a terminal program. The command will execute inside RetroShell:

[dirkwhoffmann]

This book has some decent information about RS232 communication on the C64:

Besides explaining how the user port pins map to the RS232 signals...

... it also explains how data can be received and sent via BASIC. This could be used for testing, if more complex protocols should be supported (different packet sizes, parity bits etc.):

[dirkwhoffmann]

New RS232 code is in place.

@mithrendal: From RetroShell, you can use it like this:

The following functions are provided by the public API:

/** RS232 Public API
 */
struct RS232API : API {

    class RS232 *rs232 = nullptr;

    /** @brief  Returns the component's current state.
     */
    // const RS232Info &getInfo() const;
    // const RS232Info &getCachedInfo() const;

    /** @brief  Feeds textual data into the RS232 adapter
     *  This function emulates the transmission of incoming data from an
     *  external device.
     */
    void operator<<(char c);
    void operator<<(const string &s);

    /** @brief  Read a printable byte from the incoming logbuffer.
     *  Calling this function empties the logbuffer. When the logbuffer is
     *  empty and a new data packet is received, a MSG_RS232_IN message is
     *  sent to the GUI.
     */
    std::u16string readIncoming();

    /** @brief  Read the logbuffer that records outgoing data.
     *  Calling this function empties the logbuffer. When the logbuffer is
     *  empty and a new data packet is sent, a MSG_RS232_OUT message is
     *  sent to the GUI.
     */
    std::u16string readOutgoing();

    /** @brief  Read a printable byte from the incoming logbuffer.
     */
    int readIncomingPrintableByte();

    /** @brief  Read a printable byte from the outgoing logbuffer.
     */
    int readOutgoingPrintableByte();
};

[dirkwhoffmann]

Seems to work...

Let's open a 300 Baud connection with 8 bit packets, no parity (this is the only supported format yet)...

The output appears in RetroShell...

Note: To see the output in RetroShell, RETROSHELL has to be selected as RS232 device.

[mithrendal]

@dirkwhoffmann brilliant. I merged your latest code back into vc64web which replaces my RS232 hack with your new RS232 code. It works perfectly ! 😍